The financial panic that began in the United States in 1873 and helped start the Long Depression was the Panic of 1873.
The panic followed the failure of Jay Cooke & Company on September 18, 1873. The firm had heavily promoted bonds for the Northern Pacific Railway, and its collapse damaged confidence in railroad finance. The New York Stock Exchange temporarily closed on September 20, one of the first such closures in its history.
Railroad overbuilding, speculative investment, tight credit, and monetary pressures contributed to the crisis. The shock spread internationally, including to Europe, and was followed by years of deflation and weak economic growth often called the Long Depression.
The Panic of 1873 is distinct from the Vienna stock-market crash of the same year, which occurred earlier and helped spread financial distress across Europe. It is also separate from the Panic of 1893, another major U.S. depression-era financial crisis.